Manufacture of artificial silk



Patented July 18, 1939 UNlT-ED STATES PATENroF-Flcs MANUFACTURE OF-ABTIFICIAL SILK Haul Karplus, Frankiort-on-the-Main, Germany, aasignor, by mesne assignments, to North American Rayon Corporation, a corporation of 8 Claims.

This application is a division of my applica-' tion Serial Number 233,747, filed November 16,

This invention relates to artificial silk fila-' ments having a dull lustre and to a method ior making said filaments. 1

It has already been proposed for the manuiacture oi artificial silk oi dull lustre, subsequently to impregnate the artificial silk structure, which has been prepared in the usual way, with metal salts, for'example barium sulphate, which are difiicultly soluble or insoluble in water. in such a manner that the artificial silk is treated successively with aqueous solutions of chemical compounds which by a double chemical reaction yield difficultly soluble or insoluble compounds. The artificial silk of dull lustre obtained in this way has, however, the disadvantage of an increased specific weight and at the same time diminished pliability and elasticity.

It has been -found that artificial silk filaments having a rich dull lustre, which resembles or is identical with the lustre of natural silk, can be produced by incorporating with the artificial silk filaments diificultly volatile substances, if desired a plurality of such substances in a fine state of subdivision, for instance in such a manner that these substances are distributed in an emulsion-like, or colloidal formin the spinning solutions, and these are then worked up according to the usual methods to form filaments. Under difilcultly volatile substances are also to be understood substances which are practically nonvolatile or generally considered as non-volatile. Such substances may be for example .mineral, vegetable or animal oils, fats or waxes, fatty acids, aniline, tetraline, nitro-benzene and the like, and the spinning solutions may be for instance viscose, ammoniacal copper oxide, nitrocellulose or cellulose acetate solutions. The substances to be incorporated should be so chosen for the different spinning solutions that they do not dissolve molecularly in the spinning solutions, but are merely distributed in the same after the manner of an emulsion or colloid. Solid substances such as for example thorium oxide, magnesium soaps, calcium naphthenate and the like, which are insoluble or difllcultly soluble in the spinning solutions may however also be incorporated in a finely suspended or colloidal form with the spinning solutions.

The fine distribution of the added substances in the spinning solution can be obtained for example by preparing these substances beforehand in a very fine state of subdivision or in the form of colloidal solutions and thereupon mixing them with the spinning solutions; however it may also be obtained by purely mechanical means directly in the spinning solutionsthemselves, for instance by using mixing apparatus, or distributing apparatus. The incorporated substances should preterably be distributed in such manner that, the smaller the diameter of the artificial silk filament to be spun, the finer are the distributed particles. For the usual kinds of artificial silk, particles of the size of 0.001 to 0.005 mm. are satisfactory. When distributing apparatus having a more intensive action, for instance homogenizing apparatus or emulsifying apparatus are used, it is possible if desired to obtain an even finer distribution of the substances to be incorporated, if necessary up to colloidal dimensions. Mixtures 'of difiicultly volatile with volatile substances, for example parafiin oil and benzene, are also suitable for the present process.

The substances may also be incorporated during the process for the production of the spinning solutions, that is to say the substances need not only-be distributed in the finished spinning solutions, but they can be successfully distributed beforehand, for instance at the same time as the cellulose compounds are dissolved in their solvents.

The incorporated substances are present in the finished artificial silk structures in the form of microscopicor sub-microscopic drops or granules and give the artificial silk structure a lustre similar to that of natural silk and the textiles made therefrom are extremely pliable and elastic.

According to.one mode of carrying out the invention-the method adopted'is such that the incorporated substances are subsequently partly removedagain, by which means it is possible at the same time to obtain the so-called hollow filaments. This partial elimination can be obtained for instance by treatment with suitable solvents for example, organic solvents. It can also be effected for example by removing a part of the incorporated substances as by heating, if desired, in a vacuum. By this method it is also possible partially to remove more diflicultly volatile substances from the filaments again. These artificial silk structures also have a lustre similar to that of natural silk and are characterized by a pleasant soft feel.

Ewamiples a ly distributed'by means of a butter churn, is spun in a known manner in precipitating baths, which eontainsulphuricacid'and sodium suiphate, and the resulting artificial silk filaments washedanddriediritlieusualwav. Anartisiik filament is obtained, which contains drops oi oil, distributed very finely and g. of sodium cellulose prepared and ripened in the usual manner are treated in a known way with 18-26 g. carbon disulphide, 3 g. aniline or parafiin oil then added and after thorough mixing in a kneading apparatus in a1 known manner dissolved in soda lye, so that a viscose is obtained containing 74% caustic soda and 74% cellulose. This spinning solution is spun into filaments as in Example 1, which filaments are then washed, dried and thereupon treated with benzene while being heated, until about V; of the incorporated aniline or parafiin oil is extracted from the artificial silk filaments. After evaporating the benzene, artificial silk filaments having dull lustre are obtained which are particularly soft and pliable.

Having described the invention as required by the patent statutes, what I claim is:

1. An artificial silk filament having a lustre resembling that of natural silk and containing finely divided, dispersed undissolved particles of a material of the class consisting of alkaline earth soaps and calcium naphthenate, said filament having void spaces therein.

therein, this filament having a rich dull ha alustro andcontaining ZAnairtificialsilk ent resemhiingthatoinaturalsiik m I a.

.Anartificialsilkfilamenthavingalustre resembling that oi natural silk and containing finely divided, dispersed undissolved particles of calcium naphthenate, said filament having void spaitesthe'rein.

finely divided, dispersed undissolved particles of magnesium wall.

8; An artificial silk filament having a lustre resembling that of natural silk and containing finely divided, dispersed undissolved particles oi calcium naphthenate.

HANS KARPLUB- 

